An earthquake of magnitude 3.5 occurred in the morning on Saturday 20 March 2021 at 10:22 am local time near Rennes, Ille-et-Vilaine, Bretagne, France, as reported by France's Réseau National de Surveillance Sismique (RéNaSS).

According to preliminary data, the quake was located at a shallow depth of 10 km. Shallow earthquakes are felt more strongly than deeper ones as they are closer to the surface. The exact magnitude, epicenter, and depth of the quake might be revised within the next few hours or minutes as seismologists review data and refine their calculations, or as other agencies issue their report.

Based on the preliminary seismic data, the quake should not have caused any significant damage, but was probably felt by many people as light vibration in the area of the epicenter.

Weak shaking might have been felt in Feins (pop. 770) located 3 km from the epicenter, and Combourg (pop. 5,400) 10 km away.

Other towns or cities near the epicenter where the quake might have been felt as very weak shaking include Melesse (pop. 5,700) located 15 km from the epicenter, Liffré (pop. 7,000) 18 km away, Cesson-Sévigné (pop. 16,200) 26 km away, Rennes (pop. 209,400) 27 km away, Fougères (pop. 23,700) 33 km away, Vitré (pop. 17,300) 42 km away, and St-Malo (pop. 50,700) 43 km away.